Ceramic dielectric for temperature compensating electric condensers



p 1968 ASATARO HASUMI ET AL 3,400,001

CERAMIC DIELECTRIC FOR TEMPERATURE COMPENSATING ELECTRIC CONDENSERSFiled Aug. 30, 1966 Q F13. 7- Fig.2. /0,

5,000 5' I W M/'& $8 2439/001/4/2 7am. I fi z s( fit%) Tux/Mr) 19 Fl .3.e 9

MMMQMI +l0o- 5 INVENTORS wwz g 4 $4M United States Patent I 3,400 001 1CERAMIC DIELECTRIC FOR TEMPERATURE COMPENSATING ELECTRIC CONDENSERSAsataro Hasumi, Takasakishi, Gunmaken, and Masato 3,400,001 PatentedSept. 3, 1968 In the accompanying drawing:

FIG. 1 is a graph Showing the difference of Q between embodiments of theinvention and ceramic dielectrics produced by replacing Ndgos by La O insaid embodiments;

Kogure, Annakashi, Guumakeu, Japan, assignors to 2 is graPh Showingthe.change of in case i Taiyo Yuden Company Limited, Tokyo, Japan, avarying the quantity of Nd O in one of said embodilimited-liabilitycompany of Japan merits;

Filed Aug. 30, 1966, Ser. No. 576,029 FIG. 3 1s a graph showing thechange of firing tempera- Claims priority, application Japan, Feb. 8,1966, ture in case of varying the quantity. of ZnO in one of said41/791179 1O embodiments; and 1 Claim- FIG. 4 is a graph showingcharacteristic relations between dielectric constant and temperaturecoefficient of the ceramic dielectric according to the invention andknown ceramic dielectrics. OF THE DISCLOSURE 15 The defined compositionin weight percent of the ce- Cefflm dlelectflc P temperature compensatmg616C ramic dielectric according to the invention is as follows: triccondensers, which is composed of. I caO (12 1.8)TiO2* 20.1415 P y welghtM Ti0, 260-100 CaO.xTiO (x=1.2 to 1.8) 201- 1 La O 33.0-16.4 Mg TiO 2 0-Nd O 1.6-10.6 La O 330- Bi 0 4.5-9.0 N d O 0 ZnO 8.0-2.0 B1 0 One ormore of CeO;, Pr O Sm O 6.8-0.5 Zno 80 2O *Note.-May be written thus:CaOmTiOa where a: is 9 1.2-1.8. g 68-05 Some examples of said ceramicdielectric and their S E) or characteristics, Q, dielectric constant 6,temperature com2 3 efficient Tc and firing temperature T1, are tabulatedas has a temperature coefficient of -260 to +100 10 follows:

Tail} piece Compositions (g) 0' CaTiOa T102 MgzTiOi 118203 NdzOa B140.Z110 C002, PruOn, $11120 C., a dielectric constant of 35 to 80, a Q of5000 to 10,000, and a firing temperature of 1270 to 1340 C. charactensmsTc(Xl0-/ o.) Tf( 0.) 11, 000 so -2s0 1, 270 7,900 40 +40 1,315 Thisinvention relates to ceramic dielectnc for temper- 4,900 34 +90 1, 335ature compensating electric condensers. 2 g; 1:21 In the past, asceramic dielectrics for temperature com- 6,700 00 -105 1,290

pensating electric condensers having temperature coeflicient at therange of -260 to +l00 10 C., ceramics of MgO-TiO system, CaTiO -MgTiOsystem and CaTiO -MgTiO -La O -Bi O system are known. The ceramics ofthe former two systems have firing temperature of about 1,350 C., buthave a defect of comparatively low dielectric constant of 15-30, and theceramics of the latter system have comparatively high dielectricconstant of 30-80, but have defects of comparatively high firingtemperature of 1,380-1,400 C. and low Q of ZOO-1,000.

The chief object of the invention is to provide ceramic dielectric fortemperature compensating electric condensers, which is composed of20.1-51.5 weight percent of CaO.(1.2-1.8)TiO 26.0-10.0 weight percent ofMg TiO 33.0-16.4 weight percent of La O 1.6-10.6 weight percent of Nd O4.5-9.0 weight percent of Bi O 8.0-2.0 weight percent ZnO and 6.8-0.5weight percent of one or more of CeO Pr O and Sm O and has a temperaturecoefficient at the above stated range, a comparatively high dielectricconstant of 35-80, a high Q of 5,00010,000 and a comparatively lowfiring temperature of 1,270-l,340 C.

Other features and advantages of the invention will be apparent from thefollowing description.

Raw materials of each said composition are mixed and powdered, and thenprovisionally fired at about 1,100 C. Next, after being finely powdered,they are mixed with a suitable binding material and molded underpressure, and fired at 1,270-1,340 C. in oxidizing atmosphere for aboutthree hours, whereby each said test piece is produced, and electrodesare fixed on both surfaces of said test piece to make an electriccondenser. Q and s have been measured at 1 mc., 25 C. and 70% ofhumidity, and Tc was measured at the range of 30-+85 C.

Each Q of the above stated embodiments of the invention is plotted andline a is obtained as shown in FIG. 1. When each Nd O in saidembodiments is replaced by La O each Q decreases as indicated by line a.In the embodiment No. 6, as the quantity of N0 0, increases, Qconsiderably increases to some extent as indicated by line b in FIG. 2.Further, in the embodiment No. l, as the quantity of ZnO increases, Tfconsiderably decreases to some extent as indicated by line c in FIG. 3.

The characteristic domain of the ceramic dielectric according to theinvention is the part between lines d and d in the graph showingcharacteristic relations between 9 and Tc, as shown in FIG. 4, in whichpoints 1, 2, 3, 4, 5

and 6 corresponds to the embodiments Nos. 1, 2, 3, 4, 5 and 6,respectively. Lines e and 1 indicate characteristics of the knownceramic dielectrics of MgO-TiO system and CaTiO -MgTiO system,respectively. It will be apparent from above that the ceramic dielectricaccording to the invention is superior to such known ceramic dielectricsin various characteristics.

The defined composition of the ceramic dielectric according to theinvention is due to the following reasons. If the quantity ofCaO.(l.2-1.8)Ti0 exceeds the upper limit, the dielectric constantdecreases, and if said quantity lessens to below the lower limit, firingbecomes diificult; if the quantity of Mg TiO is outside both limits, therequired characteristics are not obtained as indicated by line g in FIG.4; if the quantity of La O exceeds the upper limit, the firingtemperature increases, and if said quantity lessens to below the lowerlimit, the dielectric constant decreases; if the quantity of Nd Oexceeds the upper limit, the dielectric constant decreases, and if saidquantity lessens to below the lower limit, Q decreases as shown in FIG.2; if the quantity of BiO O exceeds the upper limit, Q decreases, and ifsaid quantity lessens to below the lower limit, the dielectric constantdecreases; if the quantity of ZnO exceeds the upper limit, Q decreases,and if said quantity lessens to below the lower limit, the firingtemperature considerably increases as shown in FIG. 3; and if thequantity of one or more of CeO Pr O and Sm O each of which serves towiden the range of firing temperature to make firing easy, exceeds theupper limit, Q decreases, and if said quantity lessens to below thelower limit, the range of firing temperature becomes short to makefiring difiicult.

What we claim is:

1. Ceramic dielectric for temperature compensating electric condensers,which is composed of 20.1-51.5 weight percent of CaO.xTiO where x is1.2-1.8, 26.0- 10.0 weight percent of Mg TiO 33.0-16.4 weight percent of1.21 0 1.6-l0.6 weight percent of Nd O 4.5-9.0 Weight percent of Bi O8.0-2.0 weight percent of ZnO, and 6.8-0.5 weight percent of at leastone member selected from the group consisting of CeO Pr O and 8111 03.

References Cited

